You've heard it before, but soda is really bad for you! That is, aside from being very high in the wrong kinds of fat from the sugary corn syrup it contains.
Soda consumption has been strongly linked with high rates of contracting diabetes, which of course is only multiplied by the factor of obesity in diabetes, which soda is also shown to cause. As if that weren't bad enough, prolonged and controlled studies on mice revealed that soda causes sickness, cancer, and death. In this case, likely due to the 4MI (4-Methylimidazole) compound (caramel coloring) typically used in photographic chemicals, dyes, cleaning and agricultural chemicals, and rubber.
Diet soda commonly contains sucralose, which is sugar (sucrose) with its hydroxyl (hydrogen/oxygen molecule) groups swapped out in favor of chlorine. Sucralose and other diet sugars such as aspartame have been linked to a 44% increased risk of heart attack or stroke. You'll also get to consume a whole host of other horrible things for absolutely no nutritional value whatsoever. Take phosphorus for example, during a study with mice (it would be illegal to give this to humans), it's conclusively demonstrated to dramatically increase the speed of aging, up to 25% at the levels contained in many common soft drinks.